Abstract Idiopathic pulmonary fibrosis (IPF) is a deadly disease (50% of patients die within 3 years), and characterized by the onset of progressive scaring of the lung of yet unknown cause. There are no curative treatments other than lung transplantation and new treatment strategies are needed desperately. We recently published that c- JUN is a central molecular mediator of many fibrotic diseases (Wernig et al., PNAS 2017). We found that induction of c-Jun in mice was sufficient to induce severe fibrosis in the lung with features of lung fibrosis in humans. Single cell mass cytometry (CyTOF) in lung fibrosis revealed that c-Jun upregulates CD47, and our preliminary data demonstrate that it was also induced in human lung fibrosis. We subsequently could demonstrate that aCD47 antibody treatment reversed c-Jun-mediated fibrosis in the lung in our lung fibrosis mouse model. Our preliminary CyTOF studies revealed that PD-L1, a second immune checkpoint protein was upregulated upon c-Jun induction, the ligand for the receptor PD1. Inhibiting the PD1/PD-L1 pathway has been recently shown to play an important role for tumor cell removal by tumor associated macrophages (Gordon et al., Nature 2017), however efficacy against IPF is yet unknown. Our preliminary data predict that blocking CD47 and PD-L1 could be highly effective in alleviating lung fibrosis in IPF. Last, we only have a sketchy understanding of the molecular mechanism underlying c-Jun induced fibrosis yet. Based on recently published work which demonstrated that transcription factors can directly regulate the expression of immune checkpoint proteins (Casey et al, Science 2016), we hypothesize that CD47 and PD-L1 are direct genomic c-Jun targets. To test this hypothesis, we propose to perform Assay of Transposase Accessible Chromatin (ATAC)-Seq experiments in lung fibroblasts derived from primary IPF patient biopsies, which we receive through our collaborator Dr. Tushar Desai, head of the IPF Study Group at Stanford, with c-Jun gain and loss of function studies. We will subsequently confirm the ATAC-Seq data with orthogonal genomic assays. Our proposed research will test efficacy of blocking the don't see me (PD-L1) and don't eat me (CD47) signals in vivo as novel anti-fibrotic treatment for IPF and help understand the underlying molecular mechanism; if successful our findings have the potential to develop fundamentally new treatment approaches for IPF. By providing a rational basis for treatment of IPF with these novel immune therapies, our research will help pave the way for future clinical trials for patients with IPF. My multidisciplinary team of mentors and collaborators consisting of my primary mentor Dr. Irving Weissman and Drs. Tushar Desai, Howard Chang, and Garry Nolan, is comprised by expert leaders in immunology, lung biology, ATAC seq and CyTOF technologies and exceptionally positioned to provide all the support and guidance needed to test my three aims and successfully complete these studies.